TY  - EJOUR
AU  - Aliu, E.
AU  - Archer, A.
AU  - Aune, T.
AU  - Barnacka, A.
AU  - Behera, B.
AU  - Beilicke, M.
AU  - Benbow, W.
AU  - Berger, K.
AU  - Bird, R.
AU  - Buckley, J. H.
AU  - Bugaev, V.
AU  - Byrum, K.
AU  - Cardenzana, J. V
AU  - Cerruti, M.
AU  - Chen, Xuhui
AU  - Ciupik, L.
AU  - Connolly, M. P.
AU  - Cui, W.
AU  - Dickinson, H. J.
AU  - Dumm, J.
AU  - Eisch, J. D.
AU  - Errando, M.
AU  - Falcone, A.
AU  - Federici, S.
AU  - Feng, Q.
AU  - Finley, J. P.
AU  - Fortin, P.
AU  - Fortson, L.
AU  - Furniss, A.
AU  - Galante, N.
AU  - Gillanders, G. H.
AU  - Griffin, S.
AU  - Griffiths, S. T.
AU  - Grube, J.
AU  - Gyuk, G.
AU  - Håkansson, N.
AU  - Hanna, D.
AU  - Holder, J.
AU  - Hughes, Gareth
AU  - Humensky, T. B.
AU  - Johnson, C. A.
AU  - Kaaret, P.
AU  - Kertzman, P. Kar M.
AU  - Khassen, Y.
AU  - Kieda, D.
AU  - Krawczynski, H.
AU  - Krennrich, F.
AU  - Kumar, S.
AU  - Lang, M. J.
AU  - Madhavan, A.
AU  - McArthur, S.
AU  - McCann, A.
AU  - Meagher, K.
AU  - Millis, J.
AU  - Moriarty, P.
AU  - Nieto, D.
AU  - de Bhróithe, A. O'Faoláin
AU  - Ong, R. A.
AU  - Orr, M.
AU  - Otte, A. N.
AU  - Park, N.
AU  - Perkins, J. S.
AU  - Pohl, Martin
AU  - Popkow, A.
AU  - Prokoph, H.
AU  - Pueschel, E.
AU  - Quinn, J.
AU  - Ragan, K.
AU  - Rajotte, J.
AU  - Reyes, L. C.
AU  - Reynolds, P. T.
AU  - Richards, G. T.
AU  - Roache, E.
AU  - Sembroski, G. H.
AU  - Shahinyan, K.
AU  - Staszak, D.
AU  - Telezhinsky, I.
AU  - Tucci, J. V.
AU  - Tyler, J.
AU  - Varlotta, A.
AU  - Vassiliev, V. V.
AU  - Wakely, S. P.
AU  - Weinstein, A.
AU  - Welsing, R.
AU  - Wilhelm, A.
AU  - Williams, D. A.
AU  - Zitzer, B.
TI  - VERITAS Observations of the BL Lac Object PG 1553+113
IS  - arXiv:1411.1439
M1  - PUBDB-2014-04306
M1  - arXiv:1411.1439
PY  - 2014
N1  - OA
AB  - We present results from VERITAS observations of the BL Lac object PG 1553+113 spanning the years 2010, 2011, and 2012. The time-averaged spectrum, measured between 160 and 560 GeV, is well described by a power law with a spectral index of 4.33 ±0.09. The time-averaged integral flux above 200 GeV measured for this period was (1.69 ±0.06) ×10<sup>−11</sup>  ph  cm<sup>−2</sup>  s<sup>−1</sup>, corresponding to 6.9% of the Crab Nebula flux. We also present the combined γ-ray spectrum from the Fermi Large Area Telescope and VERITAS covering an energy range from 100 MeV to 560 GeV. The data are well fit by a power law with an exponential cutoff at 101.9 ±3.2  GeV . The origin of the cutoff could be intrinsic to PG 1553+113 or be due to the γ-ray opacity of our universe through pair production off the extragalactic background light (EBL). Given lower limits to the redshift of z \negthinspace  >  \negthinspace 0.395 based on optical/UV observations of PG 1553+113, the cutoff would be dominated by EBL absorption. Conversely, the small statistical uncertainties of the VERITAS energy spectrum have allowed us to provide a robust upper limit on the redshift of PG 1553+113 of z \negthinspace  ≤ \negthinspace 0.62. A strongly-elevated mean flux of (2.50 ±0.14) ×10<sup>−11</sup>  ph  cm<sup>−2</sup>  s<sup>−1</sup> (10.3% of the Crab Nebula flux) was observed during 2012, with the daily flux reaching as high as (4.44 ±0.71) ×10<sup>−11</sup>  ph  cm<sup>−2</sup>  s<sup>−1</sup> (18.3% of the Crab Nebula flux) on MJD 56048. The light curve measured during the 2012 observing season is marginally inconsistent with a steady flux, giving a χ<sup>2</sup> probability for a steady flux of 0.03%.
LB  - PUB:(DE-HGF)25 ; PUB:(DE-HGF)15
UR  - https://bib-pubdb1.desy.de/record/192777
ER  -